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Phosphoribosyl modification of poly-ubiquitin chains at the Legionella-containing vacuole prohibiting autophagy adaptor recognition

Affiliations
  • 1Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA.
  • 2Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA.
  • 3Department of Computational Biology, Cornell University, Ithaca, NY, USA.
  • 4Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA. ym253@cornell.edu.
  • 5Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA. ym253@cornell.edu.

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August 30, 2024

Abstract

Ubiquitination is a posttranslational modification in eukaryotes that plays a significant role in the infection of intracellular microbial pathogens, such as Legionella pneumophila. While the Legionella-containing vacuole (LCV) is coated with ubiquitin (Ub), it avoids recognition by autophagy adaptors. Here, we report that the Sdc and Sde families of effectors work together to build ubiquitinated species around the LCV. The Sdc effectors catalyze canonical polyubiquitination directly on host targets or on phosphoribosyl-Ub conjugated to host targets by Sde. Remarkably, Ub moieties within poly-Ub chains are either modified with a phosphoribosyl group by PDE domain-containing effectors or covalently attached to other host substrates via Sde-mediated phosphoribosyl-ubiquitination. Furthermore, these modifications prevent the recognition by Ub adaptors and therefore exclude host autophagy adaptors from the LCV. In this work, we shed light on the nature of the poly-ubiquitinated species present at the surface of the LCV and provide a molecular mechanism for the avoidance of autophagy adaptors by the Ub-decorated LCV.

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